Maybe a bit more variation, perhaps make every room there in a different colour (like the cabinet in the left corner and the details around the window/hatch on the back walls). They're all red now, but make one blue, one green or something, just to make it seem a bit varied.
Perhaps in each room even a plate with a number above the window or on the floor (if it's on the floor it could be damaged/washed away a bit from all the traffic). Put bigger numbers, like 021, 304 etc.
Also maybe a bit of balance on the textures/details (like tiles or lines on the floor), an oil (or some other alien liquid) spill or a sprocket left here and there. Cause right now some areas seem to have more detail than others.
It's a nice background. On personal impression, right now it looks cartonish in way that it might be for a younger audience way, which is not bad and might be percieved differently depending on the story, characters etc., so don't take it as bad thing.